The concept in general is flawed in that you seem to be under the impression that your 3.8 pushrod is a modular V8. But the other flaw is that (if this were possible) it wouldn't be any less cheap to swap the whole engine once you factor in the expenses of new gaskets, hardware, "while you're there" items, ect.
The swap to do with a 3.8 is the splitport swap using the top end from a 99-04 V6 Mustang. There's no one stop shop to order the necessary parts from and with money being tight, ordering from somewhere will be the most expensive route to take. You need to be resourceful; do lots and lots of research on what parts you need, how to install them, things that need to be modified and such, find local pick your part junkyards, scour craigslist or car-part.com for deals, and decide what your goals are with the car.
Last edited by XR7-4.6; 11-25-2012 at 07:57 PM.